When to Cut a New Grass Lawn

When to Cut New Grass Lawn

Cutting a newly seeded or freshly turfed lawn for the first time is a crucial step in helping it establish properly. Done at the right time, mowing encourages thicker growth and helps the grass develop a strong root system. But mowing too earlyor too harshlycan damage delicate blades, uproot seedlings or stall progress. Knowing when to make that first cut gives your new lawn the best chance to thrive.

Wait for the Right Height

The best time to cut a new grass lawn is when the grass reaches a height of around five to seven centimetres. This usually takes three to six weeks after seeding, depending on the weather, soil temperature and grass type. Rushing to mow before this point risks tearing or lifting the new shoots, which are still soft and shallow-rooted. If you’re unsure whether it’s ready, gently tug on a few blades. If they lift easily, the roots aren’t developed enough for mowing.

For turf rather than seed, mowing usually happens sooner, often within ten to fourteen days of laying—once the turf has visibly rooted into the soil. Check for resistance by lifting a corner before mowing. If it stays firmly attached, it’s safe to proceed with a light first cut.

Use a High Mower Setting

The first mow should be gentle and focused on trimming rather than reducing height. Use the highest blade setting on your mower and avoid cutting more than the very tips of the grass. Removing too much at once can shock young plants and leave the lawn looking scalped or uneven. Once the lawn is established and has had several cuts, you can gradually lower the blade height over time.

Sharp mower blades are essential at this stage. Dull blades can fray or rip the grass, causing browning and encouraging disease. Before mowing, check your mower is clean and well-maintained.

Make Sure the Lawn Is Dry

Only mow when the grass is completely dry. Wet grass bends under the mower, which leads to uneven cutting and increases the risk of disease or turf damage. If the weather has been wet, wait for a dry spell before attempting the first cut. The soil should also be firm underfoot. If the ground feels soft or spongy, hold off until it settles.

Don’t Rush to Mow Again

After the first cut, allow time for the grass to recover. Let it grow again before making a second, equally light cut. Frequent mowing too soon can slow development and create stress on the grass. Once the lawn has had its first two or three mows and is growing evenly, you can begin to mow more regularly according to seasonal growth patterns.

In the early stages, mowing is less about keeping the grass short and more about encouraging healthy horizontal growth. Each cut strengthens the plant’s crown and helps the lawn fill out more evenly.

The First Cut Shapes the Lawn’s Future

The first mow of a new lawn does more than tidy the surface, it sets the direction of growth. Grass responds to cutting by producing side shoots and becoming denser. That’s why early mowing helps turn thin, upright blades into a fuller, thicker lawn. Skipping this step or delaying too long can leave the grass leggy and patchy.

Grass Grows Faster in Ideal Conditions

Newly seeded lawns grow more quickly when soil temperatures stay between 10 and 18°C and there’s consistent moisture. In spring or early autumn, you might reach mowing height in as little as three weeks. But if it’s too cold, progress slows and mowing might not happen until the fifth or sixth week. Never mow by calendaralways mow by condition.

Don't Feed Before the First Mow

It’s common to think feeding will speed up early growth, but fertilising too soon, before mowingcan lead to soft, leggy blades that are prone to collapse or disease. Let the lawn get through its first mow before applying a starter fertiliser. This ensures the roots are strong enough to support the new flush of growth and helps avoid nutrient overload.

Use a Lightweight Mower If Possible

New lawns are sensitive to pressure. A heavy mower or fast pass can rut the surface or damage shallow roots. If possible, use a smaller, lighter mower for the first few cutsor go slowly with a standard one, being careful not to turn sharply or reverse over tender turf.

Cutting Too Low Can Invite Weeds

A short first cut may expose the soil and trigger weed seed germination by allowing more sunlight to reach the ground. A longer cut not only protects new grass but also helps shade out early weeds. Once the lawn thickens and you’ve built a dense sward, it will naturally resist most weed invasions.

After First Cut, Don’t Let Grass Get Too Long Again

Once you’ve started mowing, stay consistent. Letting the lawn grow too tall again before the next cut forces it to revert to upright, patchy growth. This can undo the thickening effect and lead to uneven density. Gradual, frequent trimming is much more effective than occasional heavy mowing.

Final Word

Cutting a new grass lawn for the first time is all about patience and precision. Wait until the grass reaches the right height, make sure the soil is firm, and use a high blade setting to avoid stressing the young plants. With careful timing and a gentle approach, that first cut sets the foundation for a healthy, resilient lawn that will perform well in the months and years ahead.